1. Field of the Invention
The present invention relates to a ball joint having a dust cover thereon.
2. Description of the Prior Art
A ball joint shown in FIG. 4 is a known example of conventional ball joints.
In FIG. 4, numeral 1 denotes a socket made of steel or other metal. Socket 1 has a cylindrical through hole 2 formed therein and open at both ends. A recessed groove 3 is formed about the outer surface at one end of socket 1. A shank pestle 4 is integrally affixed to the outer surface of socket 1.
Numeral 5 denotes a ball stud made of steel or other metal having a ball portion 6 integrally formed with a shank portion 7. A stopper 8 is disport at middle part of shank portion 7. The diameter of stopper 8 is larger than the diameter of shank portion 7.
Numeral 9 denotes a ball seat made of a hard thermoplastic resin with a cylindrical outer surface fitted into socket 1. Ball seat 9 is open at one end and has flanges 10 and 11 formed on the outer surfaces of its opposed ends.
Numeral 12 denotes a cylindrical dust cover made of synthetic rubber. An attaching part 13 is disposed at one end of dust cover 12 to lock into the recessed groove 3 of socket 1. A slip 14 is formed at the other end of the dust cover to slidably attach dust cover 12 around the outer surface of shank portion 7 of ball stud 5.
Ball portion 6 of ball stud 5 is inserted, together with ball seat 9 positioned therearound, into through hole 2 of socket 1 with or without pressure. Ball portion 6 of ball stud 5 is slidably supported in ball seat 9. Shank portion 7 of ball stud 5 protrudes from ball seat 9. Flanges 10 and 11 at the ends of ball seat 9 lock over their respective ends of socket 1. Dust cover 12 is positioned to face the opening at one end of socket 1. An attaching part 13 of dust cover 12 is clamped into recessed groove 3 of socket 1 by a ring-shaped metal clip 15. Slip 14 is attached around shank 7 of ball stud 5 below stopper 8. When thus installed, dust cover 12 covers the opening of ball seat 9.
A ball joint of this type, with dust cover 12 excludeds dirt and muddy water in order to improve the life of the ball joint. However, this conventional ball joint presents a problem in that when load is applied at right angles to ball stud 5, there is a chance that a slight space may be formed between socket 1 and flange 11, thus permitting dirt and/or muddy water to enter the space between socket 1 and flange 11 and migrate along the surface of through hole 2 and into ball seat 9, where it can couse wear.
A ball joint shown in FIG. 5 is also a widely known example of conventional ball joints.
Unlike the above example shown in FIG. 4, instead of providing socket 1 with recessed groove 3 a thick catching receiver 16 is disposed at one end of ball seat 9. A flange 16 abuts one end of socket 1. A locking attaching part 13 of dust cover 12 is clamped into flange 16 by a metal clip. A recess 17 around the outer surface of the lower part of ball seat 9 provides relief to permit the ball seat 9 to easily inserted into through hole 2.
With this ball joint, part "a", where the diameter of the opening of ball seat 9 is smallest, is located beyond the end of socket 1, thus causing the drawing strength of ball stud 5 from socket 1 to be reduced. In order to improve the drawing strength of ball stud 5, it is necessary to position the smallest diameter part "a" of the opening of ball seat 9 as close as possible to the end of socket 1. However, doing this requires making socket 1 and ball stud 5 longer in the direction of the shank 7 and thereby increasing the fitting length H of ball stud 5. This is disadvantageous because the strength of ball stud 5 may suffer and the size of the entire ball joint is increased.
As described above, the conventional technique for fitting a dust cover on a ball joint has problems ability in its to seal the ball joint and in the drawing strength of the ball stud.
A major object of the present invention is to provide a ball joint with improved drawing strength of its ball stud from the socket, while maintaining satisfactory sealing with the dust cover.